The present disclosure relates to a liposome including an elastin-like polypeptide (ELP) and a tumor cell targeting material, a pharmaceutical composition including the liposome, and a method of delivering an active agent to a target site using the liposome.
Liposomes consist of at least one lipid bilayer membrane enclosing an aqueous internal compartment. Liposomes may be characterized by membrane type and by size. Small unilamellar vesicles (SUVs) have a single membrane and typically range between 20 and 50 nm in diameter. Large unilamellar vesicles (LUVs) are typically larger than 50 nm. Oligolamellar large vesicles and multilamellar vesicles have multiple, usually concentric, membrane layers and are typically larger than 100 nm. Liposomes with several nonconcentric membranes, i.e., several smaller vesicles contained within a larger vesicle, are termed multivesicular vesicles.
Liposomes are formulated to carry drugs or other active agent either contained within the aqueous interior space (water-soluble active agent) or partitioned into the lipid bilayer (water-insoluble active agent).
Active agents which have short half-lives in the bloodstream are particularly suited to delivery via liposomes. Many anti-neoplastic agents, for example, are known to have a short half-life in the bloodstream and thus, their parenteral use is not feasible. However, the use of liposomes for site-specific delivery of active agent via the bloodstream is severely limited by the rapid clearance of liposomes from the blood by cells of the reticuloendothelial system (RES).
Liposomes are not normally leaky unless a hole is formed in the liposome membrane, unless the membrane degrades or dissolves, or unless a temperature of the membrane increases to a phase transition temperature. The elevation of temperature at a target site in a subject (hyperthermia) may increase the temperature of the liposome to a phase transition temperature or higher and thus liposome contents may be released. This procedure may be used for the selective delivery of a therapeutic agent. However, this technique is limited where the phase transition temperature of the liposome is significantly higher than the normal tissue temperature.
It is accordingly desirable to devise liposome formulations capable of efficiently delivering an active agent.